U.S. patent application number 10/553511 was filed with the patent office on 2006-12-28 for high-frequency heating device and method for controlling same.
This patent application is currently assigned to Matsushita Electric Industrial Co., Ltd.. Invention is credited to Makoto Mihara, Tomotaka Nobue, Kazuho Sakamoto, Takeshi Takizaki.
Application Number | 20060289526 10/553511 |
Document ID | / |
Family ID | 33424780 |
Filed Date | 2006-12-28 |
United States Patent
Application |
20060289526 |
Kind Code |
A1 |
Takizaki; Takeshi ; et
al. |
December 28, 2006 |
High-frequency heating device and method for controlling same
Abstract
A problem of the invention is to provide a high frequency
heating apparatus capable of realizing excellent heating without an
irregularity in heating even for a thick-walled heated object. In
order to resolve the above-described problem, according to a high
frequency heating apparatus of the invention, a high frequency
heating apparatus 1 for heating a heated object by irradiating a
microwave having a frequency of 5.8 GHz to the heated object is
constituted by mounting a plurality of pieces of wave guides 11a,
11b having feeding ports 7, 9 for emitting microwaves into a cavity
3 partitioning a heating chamber 2.
Inventors: |
Takizaki; Takeshi;
(Souraku-gun, JP) ; Nobue; Tomotaka;
(Yamatokoriyama-shi, JP) ; Sakamoto; Kazuho;
(Souraku-gun, JP) ; Mihara; Makoto; (Nara-shi,
JP) |
Correspondence
Address: |
PEARNE & GORDON LLP
1801 EAST 9TH SRTEET
SUITE 1200
CLEVELAND
OH
44114-3108
US
|
Assignee: |
Matsushita Electric Industrial Co.,
Ltd.
1006, Oaza Kadoma Kadoma-shi
Osaka
JP
571-8501
|
Family ID: |
33424780 |
Appl. No.: |
10/553511 |
Filed: |
April 23, 2004 |
PCT Filed: |
April 23, 2004 |
PCT NO: |
PCT/JP04/05889 |
371 Date: |
June 23, 2006 |
Current U.S.
Class: |
219/746 |
Current CPC
Class: |
H05B 6/708 20130101;
H05B 2206/044 20130101; H05B 6/80 20130101; H05B 6/745 20130101;
H05B 6/763 20130101; H05B 6/6402 20130101; H05B 6/707 20130101 |
Class at
Publication: |
219/746 |
International
Class: |
H05B 6/74 20060101
H05B006/74 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 25, 2003 |
JP |
2003-121876 |
May 8, 2003 |
JP |
2003-130370 |
May 9, 2003 |
JP |
2003-131804 |
Claims
1. A high frequency heating apparatus in that a microwave of 5.8
GHZ is irradiated to an object in a heating chamber in order to
heat the object; wherein a plurality of pieces of wave guides
having feeding ports for emitting the microwave are mounted to a
cavity partitioning the heating chamber.
2. The high frequency heating apparatus according to claim 1,
wherein a wall face of the cavity arranged with the feeding port is
constituted by upper and lower faces, or the upper face and a side
face, or the side face and the lower face of the heating
chamber.
3. The high frequency heating apparatus according to claim 1,
wherein two pieces of the feeding ports are provided to the upper
face of the heating chamber by at least two pieces of the wave
guides arranged at an upper wall of the cavity.
4. The high frequency heating apparatus according to claim 3,
wherein the at least two pieces of wave guides at the upper wall of
the cavity are arranged vertically to direct long sides of
cross-sectional faces of the wave guides in an up and down
direction.
5. The high frequency heating apparatus according to claim 4,
wherein a face heater is arranged at a region of the upper wall of
the cavity excluding a region of mounting the wave guides arranged
vertically.
6. A high frequency heating apparatus comprising: a high frequency
generating portion; and a heating chamber constituted by a ceiling,
a side wall and a floor portion for heating to process a heated
object by applying a high frequency wave from the high frequency
generating portion; wherein a wide range wave guide in a shape of a
parallelepiped constituted by including a number of feeding ports
is provided on a rear side of the heating chamber, and the high
frequency generating portion is provided at immediate proximity of
the wide range wave guide of the shape of the parallelepiped.
7. The high frequency heating apparatus according to claim 6,
wherein the wide range wave guide in the shape of the
parallelepiped is constituted by a size widened substantially over
an entire face of the floor portion and the number of feeding ports
are provided on a rear side of the floor portion to direct to a
side of the floor portion.
8. The high frequency heating apparatus according to claim 6,
wherein the wide range wave guide in the shape of the
parallelepiped is constituted by a size widened substantially over
an entire face of the ceiling and the number of feeding ports are
provided on a rear side of the ceiling to direct to a side of the
ceiling.
9. The high frequency heating apparatus according to any one of
claims 6 through 8, wherein a frequency of the high frequency wave
supplied from the high frequency generating portion is 5.8 GHz.
10. The high frequency heating apparatus according to claim 6,
wherein sizes of the number of pieces of feeding ports are smaller
at a vicinity of the high frequency generating portion and the
remoter from the high frequency generating portion, the larger the
sizes.
11. A high frequency heating apparatus for heating an object to be
heated, comprising: a heating chamber for containing the object; a
high frequency generating portion for supplying a high frequency
wave to the heating chamber; wherein the high frequency generating
portion includes a first high frequency generating portion for
generating the high frequency wave having a frequency of 2.45 GHz
and a second high frequency generating portion for generating the
high frequency wave having a frequency of 5.8 GHz.
12. The high frequency heating apparatus according to claim 11,
further comprising: a first inverter circuit for supplying a drive
power to the first high frequency generating portion; a second
inverter circuit for supplying a drive power to the second high
frequency generating portion; and a drive control portion for
simultaneously or alternately driving the first high frequency
generating portion and the second high frequency generating portion
by the inverter circuits.
13. The high frequency heating apparatus according to claim 11,
further comprising: a single inverter circuit for supplying a drive
power to the first high frequency generating portion and the second
high frequency generating portion; and a drive control portion for
alternately switching to feed electricity to drive the first high
frequency generating portion and the second high frequency
generating portion.
14. The high frequency heating apparatus according to claim 11,
further including: an upper side feeding port provided at an upper
face of the heating chamber for introducing the high frequency wave
into the heating chamber; and a lower side feeding port provided at
a lower face of the heating chamber for introducing the high
frequency wave into the heating chamber; wherein the high frequency
wave from the first high frequency generating portion or the second
high frequency generating portion is introduced individually from
respectives of the upper side feeding port and the lower side
feeding port.
15. The high frequency heating apparatus according to claim 14,
further comprising: a partition plate for dividing a space of the
heating chamber upward and downward.
16. The high frequency heating apparatus according to claim 15,
wherein the partition plate includes a high frequency heat
generating member for generating heat by being irradiated with the
high frequency wave.
17. The high frequency heating apparatus according to any one of
claims 14 through 16, wherein the high frequency wave from the
second high frequency generating portion is introduced into the
heating chamber from the upper side feeding port of the heating
chamber.
18. The high frequency heating apparatus according to claim 11,
wherein the heating chamber includes a heating chamber main body
having an opening portion, and an opening/closing door for openably
and closably covering the opening portion, and at least one of
portions of the heating chamber main body and the opening/closing
door opposed to each other is formed with a choke for preventing
leakage of a radio wave; and wherein the choke shields the high
frequency waves respectively from the first high frequency
generating portion and the second high frequency generating
portion.
19. A method of controlling a high frequency heating apparatus
which is a method of controlling a high frequency heating apparatus
for heating to process a heated object by supplying a high
frequency wave from a high frequency generating portion to a
heating chamber containing the heated object; wherein the high
frequency wave having a frequency of 2.45 GHz and the high
frequency wave having a frequency of 5.8 GHz are simultaneously or
alternately supplied from the high frequency generating portion to
the heating chamber.
20. The method of controlling a high frequency heating apparatus
according to claim 19, wherein the high frequency wave having
either one of the respective frequencies is outputted at an initial
stage of heating and the high frequency wave having other of the
respective frequencies is started to output after elapse of a
predetermined time period or after reaching a predetermined
temperature from starting to heat the heated object.
21. The method of controlling a high frequency heating apparatus
according to claim 19, wherein when the high frequency waves having
the respective frequencies are simultaneously outputted, an output
of at least either one of the respective high frequency waves is
restricted such that a total of a drive power for outputting the
high frequency waves does not exceed a rated power of the high
frequency heating apparatus.
Description
TECHNICAL FIELD
[0001] The present invention relates to a high frequency heating
apparatus for heating an object to be heated by supplying a high
frequency wave to a heating chamber containing the object and its
control method.
BACKGROUND ART
[0002] A high frequency apparatus having high frequency generating
means (magnetron) for outputting a microwave into a heating chamber
accommodating an object to be heated has rapidly been spread as a
microwave oven which is a heating cooking apparatus of a foodstuff
or the like since the object in the heating chamber can be heated
in a short period of time and efficiently.
[0003] Meanwhile, according to the microwave oscillated into the
heating chamber, when there is not electromagnetic wave stirring
means in the heating chamber, a standing wave is formed by
reflection at an inner wall face of a cavity partitioning the
heating chamber and heating spots are produced at intervals of
about a half of a wavelength of the standing wave.
[0004] In the case of a house use microwave oven of a background
art, the microwave oven is mounted with a magnetron for oscillating
a microwave having a frequency of 2.45 GHz and in this case, a
wavelength of a generated standing wave becomes about 12
centimeters, heating spots are produced at intervals of about 6
centimeters of a half thereof, in comparison with a size of a food
stuff heated in a general household or the like, the interval of
the heating spots is large to cause an irregularity in heating.
[0005] Hence, the microwave oven of the background art is equipped
with a turn table for rotating the food product in the heating
chamber or electromagnetic wave stirring means of a stirrer fan for
stirring the electromagnetic wave in the heating chamber or the
like in order to reduce an influence of the standing wave causing
the irregularity in heating.
[0006] However, the equipments make a movable part penetrated
through a wall portion of the cavity partitioning the heating
chamber indispensable, a structure of attaching the movable part
onto the cavity for preventing leakage of the electromagnetic wave
at the cavity penetrating portion by the movable part is
complicated to bring about an increase in cost of fabrication cost
by an increase in constituent parts or large-sized formation of the
apparatus.
[0007] Hence, recently, there have been carried out researches on
prevention of an irregularity in heating on a heated object from
being brought about by contracting an interval of heated spots
constituting a half of a wavelength of a standing wave by changing
a frequency of a microwave used without being equipped with a turn
table or electromagnetic stirring means of a stirrer fan or the
like and a microwave of 5.8 GHz has been proposed to use (refer to,
for example, Patent Reference 1).
[0008] (Patent Reference 1)
[0009] JP-A-3-203191
[0010] According to an microwave oven using a microwave of 5.8 GHz,
when a standing wave is formed by reflection of the microwave by an
inner wall face of a cavity, a wavelength of the standing wave
becomes about 5 cm, an interval of heating spots in a heating
chamber becomes 2.5 cm of a half of the wavelength, in comparison
with an microwave oven using a microwave of 2.45 GHz, a density of
distributing the heating spots on a surface of a heated object is
increased, the interval of the heating spots is not excessively
larger than a size of a general food stuff and therefore, an
irregularity in heating can be restrained from being brought out
without being equipped with the electromagnetic wave stirring means
of the background art, and by deleting the electromagnetic stirring
means, simplification of the structure, small-sized formation of
the apparatus in accordance with the simplification, or a reduction
in fabrication cost or running cost can be achieved.
[0011] On the other hand, according to the microwave of 5.8 GHz,
when compared with the microwave of 2.45 GHz, a heating depth to an
inner portion of the heated object becomes shallow and therefore,
as shown by FIG. 9, although a heating distribution characteristic
at a surface of the heated object is more excellent than that of
the microwave of 2.45 GHz, a heating characteristic thereof to an
inner portion of the heated object becomes inferior to that of the
microwave of 2.45 GHz.
[0012] As a result, according to a constitution of oscillating the
microwave from a single feeding port into the heating chamber as in
the microwave oven of the background art disclosed in Patent
Reference 1, mentioned above, when a thickness of the heated object
constituting an object of heating is thick, although a surface
layer on a side on which the microwave is easy to impinge can
sufficiently be heated, with regard to a surface layer on other
side and an inner portion of the heated object, there is a concern
of bringing about an irregularity in heating or a deficiency in
heating.
[0013] It is an object of the invention to provide a high frequency
heating apparatus capable of irradiating a microwave to a surface
of a heated object in a wider range, capable of realizing to heat
even a thick-walled heated object excellently without an
irregularity in heating, further, capable of achieving
simplification of a structure, small-sized formation of an
apparatus in accordance therewith, or a reduction in fabrication
cost or running cost by enabling to omit electromagnetic wave
stirring means.
[0014] Further, according to a high frequency heating apparatus of
a background art, a high frequency generating portion of a
magnetron is provided on an outer side of a heating chamber, a high
frequency wave is guided by passing the high frequency wave through
a wave guide therefrom to a large single piece feeding port
provided at any of a ceiling, a side wall, a floor portion of the
heating chamber and the high frequency wave is guided into the
heating chamber from the feeding port (refer to, for example,
Patent Reference 2).
[0015] (Patent Reference 2)
[0016] JP-A-3-203191
[0017] FIG. 14 is a vertical sectional view showing an inner
structure of the high frequency heating apparatus of the background
art described in Patent Reference 2. In the drawing, numeral 150
designates the high frequency heating apparatus of the background
art, numeral 151 designates the heating chamber, numeral 152
designates the high frequency generating portion provided on the
outer side of the heating chamber 151 and including the magnetron
for oscillating a microwave of a frequency of 2.45 GHz, numeral 153
designates the wave guide, and numeral 154 designates the feeding
port. Numeral 155 designates a turn table, numeral 156 designates a
motor for driving to rotate the turn table 155, numeral 157
designates a door, and numeral 158 designates radio wave leakage
preventing means having a choke structure in correspondence with a
quarter wavelength of the microwave provided to four corners of the
door 157. Notation G designates the heated object mounted on the
turntable 155.
[0018] When the magnetron 152 is driven, the microwave having the
frequency of 2.45 GHz oscillated from the magnetron 152 is
irradiated from the feeding port 154 into the heating chamber 151
by passing the wave guide 153, and reflected by a metal wall of the
heating chamber 151 to generate a standing wave at inside of the
heating chamber 151. In the case of the microwave having the
frequency of 2.45 GHz, the wavelength becomes about 12 cm and
therefore, an interval of the standing wave generated in the
heating chamber 151 produced by reflecting the microwave by the
metal wall of the heating chamber 151 becomes about 6 cm of a half
thereof and the microwave is absorbed by the heated object G to
heat the heated object G at a portion of an antinode thereof having
a strong electric field.
[0019] However, the interval of about 6 cm constitutes an
irregularity for the heated object G and therefore, an electric
field on the heated object G is disturbed by slowly rotating the
turntable 155 by the motor 56 to prevent the standing wave from
being generated on the heated object G.
[0020] In this way, according to the high frequency heating
apparatus 150 of the background art, in order to carry out heating
without irregularity, the turn table 155 and the motor 156 are
needed and therefore, the structure is complicated, reliability is
deteriorated and cost is increased.
[0021] As a constitution of resolving the drawback, there is the
high frequency heating apparatus of the embodiment described in
Patent Reference 2. FIG. 15 illustrates views showing an inner
structure of the high frequency heating apparatus of the embodiment
described in Patent Reference 2, FIG. 15(a) is a vertical sectional
view, and FIG. 15(b) is a cross-sectional view passing a wave guide
53 of FIG. 15(a).
[0022] In FIG. 15(a), numeral 160 designates the high frequency
heating apparatus of the embodiment, numeral 161 designates a
heating chamber, numeral 162 designates a high frequency generating
portion provided on an outer side of the heating chamber 161 and
including a magnetron for oscillating a microwave having a
frequency of 5.8 GHz, numeral 163 designates a wave guide, numeral
164 designates a feeding port. Numeral 165 designates a table for
mounting a heated object, numeral 167 designates a door, and
numeral 168 designates radio wave leakage preventing means of a
choke structure provided at four corners of the door 167 in
correspondence with a quarter wavelength of the microwave. Notation
G designates a heated object mounted on the table 165.
[0023] Further, in FIG. 15(b), a single piece of the feeding port
164 is provided at a front end of the narrow wave guide 153 having
a width substantially equal to a lateral width of the high
frequency generating portion 162, and the microwave oscillated from
the high frequency generating portion 162 is irradiated into the
heating chamber 161 only from the feeding port 164.
[0024] Hence, when the magnetron 162 is driven, the microwave
having the frequency of 5.8 GHz oscillated from the magnetron 162
is irradiated into the heating chamber 161 from the feeding port
164 by passing the wave guide 163 and is reflected by a metal wall
of the heating chamber 161 to generate a standing wave at inside of
the heating chamber 161. In the case of the microwave having the
frequency of 5.8 GHZ, the wavelength becomes about 5.17 cm and
therefore, the interval of the standing wave generated in the
heating chamber 161 by reflecting the microwave by the metal wall
of the heating chamber 161 becomes about 2.6 cm of a half thereof,
the microwave is absorbed by the heated object G at a portion of an
antinode having a strong electric field to heat the heated object G
Further, the interval of about 2.6 cm is small for the heated
object G and therefore, a conspicuous irregularity is not
constituted.
[0025] Therefore, the turn table and the motor serving as described
above are not needed and therefore, the structure becomes simple,
the reliability is promoted and the cost becomes inexpensive.
[0026] Although the irregularity in heating becomes inconspicuous
since the interval of the standing wave generated in the heating
chamber 161 becomes about 2.6 cm of a half thereof because the high
frequency heating apparatus 160 of FIG. 15 uses the magnetron for
oscillating the microwave having the frequency of 5.8 GHZ in this
way, more or less irregularity is still produced.
[0027] Further, the feeding port 164 is provided only at a center
of a ceiling of the heating chamber 161 and therefore, there is
brought about a difference in an electric field intensity of the
microwave between a center and a corner of the heating chamber 161
and therefore, there is brought about a difference in heating
between a center and an end of the heated object G.
[0028] It is an object of the invention to resolve the drawback to
provide a high frequency heating apparatus capable of making an
irregularity in heating further inconspicuous and capable of
effectively utilizing a space at a vicinity of a center portion on
a rear side of a floor portion of the heating chamber without
producing a difference in an electric field intensity of a
microwave between a center and a corner of the heating chamber.
[0029] Heretofore, there has widely been utilized a high frequency
heating apparatus for heating and cooking a heated object by
supplying a high frequency wave to a heating chamber containing a
heated object for heating and cooking a food stuff. The high
frequency heating apparatus of this kind is mounted with a
magnetron for generating a high frequency wave having a frequency
of 2.45 GHz for supplying the generated high frequency wave into
the heating chamber. A standing wave is formed in the heating
chamber by supplying the high frequency wave, a wavelength of the
generated standing wave becomes about 12 cm, and substantially
heating spots having a strong electric field are produced at an
interval of about 6 cm of a half thereof. However, the interval of
the heating spots is longer than a size of a food stuff to be
heated and cooked and therefore, a density of distributing the
heating spots which can be present in the food stuff becomes low,
the food stuff is partially heated and an irregularity in heating
tends to be liable to be produced.
[0030] Hence, there is proposed a technology for reducing the
irregularity in heating the heated object by narrowing the interval
of the heating spots by changing the frequency of the high
frequency used from 2.45 GHz to 5.8 GHz to thereby increase the
density of distributing the heating spots (refer to, for example,
Patent Reference 3).
[0031] (Patent Reference 3)
[0032] JP-A-3-203191
[0033] However, whereas according to the high frequency of 5.8 GHz,
the density of distributing the heating spots becomes higher than
that of the high frequency of 2.45 GHz, a depth thereof of being
absorbed to the heated object becomes shallow and therefore, when
the heated object is thick-walled, an irregularity in heating in
which a surface of the heated object is mainly heated and an inner
portion of the heated object is deficient in heating is liable to
be brought about.
[0034] Therefore, in the case of the high frequency of 5.8 GHz the
heating distribution of which becomes dense, although when the
heated object is thin-walled, an excellent uniform heating effect
can be expected, with regard to the thick-walled heated object, the
irregularity in heating is increased in the depth direction, as a
result, uniform heating becomes difficult. Further, although in the
case of a thick wall, the inner portion is heated from the surface
of the heated object by heat conduction, time is taken until
conducting heat to the inner portion and a rapid heating effect
which is the best advantage of high frequency heating is not
achieved.
[0035] The invention has been carried out in consideration of the
above-described situation and it is an object thereof to provide a
high frequency heating apparatus capable of carrying out a uniform
heating processing swiftly even in the case of a thick-walled
heated object by restraining an irregularity in heating from being
brought about.
DISCLOSURE OF THE INVENTION
[0036] A high frequency heating apparatus according to the
invention for achieving the above-described object is characterized
in a high frequency heating apparatus for heating a heated object
by irradiating a microwave of 5.8 GHz to the heated object in a
heating chamber, wherein a plurality of pieces of wave guides
having feeding ports for emitting the microwave are mounted to a
cavity partitioning the heating chamber.
[0037] According to the high frequency heating apparatus
constituted in this way, a distribution of heating spots by the
microwave is widened by a plurality of the feeding ports by a
plurality of pieces of the wave guides and the microwave can be
made to impinge on a portion of a wider range of a surface of the
heated object.
[0038] As a result, even in the case of a microwave of 5.8 GHz
having a shallow baking depth, a substantial baking depth can be
intensified to double by heating the heated object from, for
example, two directions opposed to each other.
[0039] Further, in order to compensate for a drawback that a baking
depth of the microwave of 5.8 GHz is shallow, from a view point of
increasing faces on the heated object on which the microwave is
made to impinge, it is preferable to mount the feeding ports for
emitting the microwaves dispersingly at a plurality of wall faces
of the cavity, specifically, as described in Claim 2, there may be
constructed a constitution in which that a wall face of the cavity
arranged with the feeding port is constituted by upper and lower
faces, or the upper face and a side face, or the side face and the
lower face of the heating chamber.
[0040] Further, from a view point of uniformly dispersing
irradiation of the microwave from the upper face to the heated
object in the heating chamber in a wide range, as described in
Claim 3, there may be constructed a constitution in which two
pieces of the feeding ports are provided to the upper face of the
heating chamber by at least two pieces of the wave guides arranged
at an upper wall of the cavity.
[0041] Further, the high frequency heating apparatus described in
Claim 4 is characterized in that the at least two pieces of wave
guides at the upper wall of the cavity are arranged vertically to
direct long sides of cross-sectional faces of the wave guides in an
up and down direction in the high frequency heating apparatus
described in Claim 3.
[0042] A cross-sectional area of a wave guide for guiding a
microwave of 5.8 GHz is contracted to about 1/4 of a
cross-sectional area of a wave guide for guiding a microwave of
2.45 GHz. Therefore, a long side dimension of the wave guide for
5.8 GHz is to a degree substantially the same as a short side
dimension of the wave guide for 2.45 GHz.
[0043] Therefore, even when a space of installing a wave guide
ensured on a side of the upper face of the cavity is set to be
equivalent to that of the high frequency heating apparatus of the
background art in which the wave guide for 2.45 G-Hz is installed
at the upper face of the cavity by directing the long side
horizontally, the wave guide for 5.8 GHz can be mounted to be
arranged vertically to direct the long side vertically. Further, by
constructing a constitution of mounting to arrange the wave guide
vertically in this way, an area occupied by the wave at the upper
face of the cavity can be contracted.
[0044] As a result, a vacant space is increased at the upper face
of the cavity and when there is constructed a constitution in which
a face heater is arranged at a region of the upper wall of the
cavity excluding a region of mounting the wave guides arranged
vertically as described in Claim 5, a region of mounting the face
heater can be enlarged, a temperature distribution in an oven
heating processing operating the face heater can be made to be
uniform in a wider region and oven heating without an irregularity
in heating can be realized.
[0045] Further, a high frequency heating apparatus of the invention
is characterized in a high frequency heating apparatus including a
high frequency generating portion, and a heating chamber
constituted by a ceiling, a side wall and a floor portion for
heating to process a heated object by applying a high frequency
wave from the high frequency generating portion, wherein a wide
range wave guide in a shape of a parallelepiped constituted by
including a number of feeding ports is provided on a rear side of
the heating chamber, and the high frequency generating portion is
provided at immediate proximity of the wide range wave guide of the
shape of the parallelepiped.
[0046] According to the above-described constitution, a structure
of the wave guide is constituted by a structure having a wide width
and therefore, a number of feeding ports can be provided and
heating can be made to be proximate to uniform heating.
[0047] Further, the high frequency heating apparatus of the
invention is characterized in that the wide range wave guide in the
shape of the parallelepiped is constituted by a size widened
substantially over an entire face of the floor portion and the
number of feeding ports are provided on a rear side of the floor
portion to direct to a side of the floor portion.
[0048] According to the above-described constitution, substantially
a total of a rear side of the floor portion is constituted by a
structure of the wave guide, substantially the total face of the
floor portion is provided with the number of feeding ports and
therefore, there is not brought about a difference in an electric
field intensity of the microwave between a center and a corner of
the heating chamber and heating can be made to be proximate to
uniform heating. Further, owing to irradiation of the microwave
from the floor portion, the irradiation is proximate to the heated
portion and also a heating efficiency is improved.
[0049] Further, a constitution of a turntable, a rotational antenna
or the like for stirring radio wave may not be provided and
therefore, reliability against radio wave spark, radio wave leakage
or the like is also promoted.
[0050] Further, the high frequency heating apparatus of the
invention is characterized in that the wide range wave guide in the
shape of the parallelepiped is constituted by a size widened
substantially over an entire face of the ceiling and the number of
feeding ports are provided on a rear side of the ceiling to direct
to a side of the ceiling.
[0051] According to the above-described constitution, substantially
the total of the rear side of the ceiling is constituted by the
structure of the wave guide, a number of feeding ports are provided
at substantially a total face and therefore, uniform radio wave
falls from a single face of the ceiling as in a shower and
therefore, further uniform heating can be carried out.
[0052] Further, the high frequency heating apparatus of the
invention is characterized in that a frequency of the high
frequency wave supplied from the high frequency generating portion
is 5.8 GHz.
[0053] According to the above-described constitution, an interval
of standing waves becomes narrower than that in the case in which
the wave length of the microwave is 2.45 GHz constituting the main
current of the background art and therefore, heating can be made to
be proximate to further uniform heating.
[0054] Further, the high frequency heating apparatus of the
invention is characterized in that sizes of the number of pieces of
feeding ports are smaller at a vicinity of the high frequency
generating portion and the remoter from the high frequency
generating portion, the larger the sizes.
[0055] According to the above-described constitution, there is not
brought about a difference in the electric field intensity of the
microwave between a vicinity of the high frequency generating
portion and a portion remote from the high frequency generating
portion and heating can be made to be proximate to further uniform
heating.
[0056] Further, the object of the invention is achieved by
constitutions described below.
[0057] (1) A high frequency heating apparatus which is a high
frequency heating apparatus for heating to process a heated object
by supplying a high frequency wave from a high frequency generating
portion to a heating chamber for containing the heated object,
wherein the high frequency generating portion includes a first high
frequency generating portion for generating the high frequency wave
having a frequency of 2.45 GHz and a second high frequency
generating portion for generating the high frequency wave having a
frequency of 5.8 GHz.
[0058] According to the high frequency heating apparatus, two kinds
of the high frequency waves of the high frequency wave having a
frequency of 2.45 GHz having a high heating effect and the high
frequency wave having a frequency of 5.8 GHz a heating distribution
of which is uniform can be supplied to the heating chamber, an
irregularity in heating is restrained from being brought about, and
even the thick-walled heated object can be heated to process
swiftly and uniformly.
[0059] (2) The high frequency heating apparatus described in (1),
further including a first inverter circuit for supplying a drive
power to the first high frequency generating portion, a second
inverter circuit for supplying a drive power to the second high
frequency generating portion, and a drive control portion for
simultaneously or alternately driving the first high frequency
generating portion and the second high frequency generating portion
by the inverter circuits.
[0060] According to the high frequency heating apparatus, powers of
driving the first high frequency generating portion and the second
high frequency generating portion are supplied by respectively
separate inverter circuits and therefore, the high frequency waves
can be outputted from the respective high frequency generating
portions simultaneously or alternately, further, also output
intensities can be made variable and therefore, even a complicated
heating pattern can simply be controlled.
[0061] (3) The high frequency heating apparatus described in (1),
further including a single inverter circuit for supplying a drive
power to the first high frequency generating portion and the second
high frequency generating portion, and a drive control portion for
alternately switching to feed electricity to drive the first high
frequency generating portion and the second high frequency
generating portion.
[0062] According to the high frequency heating apparatus,
electricity can be controlled to feed to the first high frequency
generating portion and the second high frequency generating portion
by the single inverter circuit and therefore, a circuit
constitution of the drive control portion is simplified, and a
space needed for installing thereof is reduced, which can
contribute to the small-sized and the light-weighted formation of
the apparatus.
[0063] (4) The high frequency heating apparatus described in any
one of (1) through (3), further including an upper side feeding
port provided at an upper face of the heating chamber for
introducing the high frequency wave into the heating chamber, and a
lower side feeding port provided at a lower face of the heating
chamber for introducing the high frequency wave into the heating
chamber, wherein the high frequency wave from the first high
frequency generating portion or the second high frequency
generating portion is introduced individually from respectives of
the upper side feeding port and the lower side feeding port.
[0064] According to the high frequency heating apparatus, the high
frequency wave from the first high frequency generating portion or
the second high frequency generating portion is introduced from
respectives of the upper side feeding port and the lower side
feeding port individually to the heating chamber and therefore, the
respective high frequency waves can be irradiated from an optimum
position in accordance with heating characteristics of the high
frequency waves.
(5) The high frequency heating apparatus described in (4), further
including a partition plate for dividing a space of the heating
chamber upward and downward.
[0065] According to the high frequency heating apparatus, by diving
a space of the heating chamber upward and downward, one of the high
frequency waves can be supplied to an upper side space, other of
the high frequency waves can be supplied to a lower side space, and
the heated object can be heated by supplying the respective high
frequency waves to the individual spaces.
(6) The high frequency heating apparatus described in (5), wherein
the partition plate includes a high frequency heat generating
member for generating heat by being irradiated with the high
frequency wave.
[0066] According to the high frequency heating apparatus, the high
frequency heat generating member of the partition plate generates
heat by being irradiated with the high frequency wave and
therefore, a cooking mark can be attached to the heated object by
heating the heated object mounted on the partition plate by
irradiation heat or conduction heat. Further, a preheating effect
can be provided by warming the heating chamber.
[0067] (7) The high frequency heating apparatus described in any
one of (4) through (6), wherein the high frequency wave from the
second high frequency generating portion is introduced into the
heating chamber from the upper side feeding port of the heating
chamber.
[0068] According to the high frequency heating apparatus, the high
frequency wave of 5.8 GHz from the second high frequency heating
portion is supplied from the upper side feeding port and therefore,
the heated object in the heating chamber can uniformly be
heated.
[0069] (8) The high frequency heating apparatus described in any
one of (1) through (7), wherein the heating chamber includes a
heating chamber main body having an opening portion, and an
opening/closing door for openably and closably covering the opening
portion, and at least one of portions of the heating chamber main
body and the opening/closing door opposed to each other is formed
with a choke for preventing leakage of a radio wave, and wherein
the choke shields the high frequency waves respectively from the
first high frequency generating portion and the second high
frequency generating portion.
[0070] According to the high frequency heating apparatus, although
the choke is small-sized, when the opening/closing door is closed,
the high frequency waves having two kinds of different frequencies
supplied to inside of the heating chamber are not leaked.
[0071] (9) A method of controlling a high frequency heating
apparatus which is a method of controlling a high frequency heating
apparatus for heating to process a heated object by supplying a
high frequency wave from a high frequency generating portion to a
heating chamber containing the heated object, wherein the high
frequency wave having a frequency of 2.45 GHz and the high
frequency wave having a frequency of 5.8 GHz are simultaneously or
alternately supplied from the high frequency generating portion to
the heating chamber.
[0072] According to the method of controlling the high frequency
heating apparatus, by supplying the high frequency wave having the
frequency of 2.45 GHz and the high frequency wave having the
frequency of 5.8 GHz simultaneously or alternately to the heating
chamber, the high frequency wave of 2.45 GHz having the high
heating effect and the high frequency of 5.8 GHz the uniform
heating effect of which is high can selectively be supplied and
therefore, an efficient heating processing can be carried out by
supplying a pertinent high frequency wave in accordance with a
shape of the heated object or a heating object.
[0073] (10) The method of controlling a high frequency heating
apparatus described in (9), wherein the high frequency wave having
either one of the respective frequencies is outputted at an initial
stage of heating and the high frequency wave having other of the
respective frequencies is started to output after elapse of a
predetermined time period or after reaching a predetermined
temperature from starting to heat the heated object.
[0074] According to the method of controlling the high frequency
heating apparatus, by supplying the high frequency wave having the
frequency of 2.45 GHz having the high heating effect at an initial
stage of heating to elevate a temperature of the heated object in
one motion, further, supplying the high frequency wave having the
frequency of 5.8 GHz after elapse of a predetermined time period or
after reaching a predetermined temperature, uniform formation of
the heating temperature is achieved, and a state of uniformly
heating the heated object with a small temperature distribution can
be constituted. Further, when the high frequency wave of 5.8 GHz is
precedingly supplied and the high frequency wave of 2.45 GHz is
successively supplied contrary thereto, there is constituted a
heating pattern preferable for cooking or the like of strongly
heating the heated object at a latter half of heating.
[0075] (11) The method of controlling a high frequency heating
apparatus described in (9) or (10), wherein when the high frequency
waves having the respective frequencies are simultaneously
outputted, an output of at least either one of the respective high
frequency waves is restricted such that a total of a drive power
for outputting the high frequency waves does not exceed a rated
power of the high frequency heating apparatus.
[0076] According to the method of controlling the high frequency
heating apparatus, when the outputs of the respective high
frequency waves exceed the rated power, a total of drive powers for
outputting the high frequency waves can be made to be prevented
from exceeding the rated power of the high frequency heating
apparatus by restricting the output of either one of the high
frequency waves.
BRIEF DESCRIPTION OF THE DRAWINGS
[0077] FIG. 1 is a sectional view of a first embodiment of a high
frequency heating apparatus according to the invention,
[0078] FIG. 2 is a sectional view of a second embodiment of the
high frequency heating apparatus according to the invention,
[0079] FIG. 3 is a perspective view of a third embodiment of the
high frequency heating apparatus according to the invention,
[0080] FIG. 4(a) is a cross-sectional view of a wave guide for
guiding a microwave of 2.4 GHz, and FIG. 4(b) is a cross-sectional
view of a wave guide for guiding a microwave of 5.8 GHz,
[0081] FIG. 5 is a perspective view of a fourth embodiment of the
high frequency heating apparatus according to the invention,
[0082] FIG. 6 is a sectional view taken along a line A-A of FIG.
5,
[0083] FIG. 7 illustrates sectional views of a fifth embodiment of
the high frequency heating apparatus according to the invention,
and FIG. 7(a) and Fig. (b) are views showing electric lines of
force of heating distributions which differ from each other,
[0084] FIG. 8 is a plane view of a sixth embodiment of the high
frequency heating apparatus according to the invention,
[0085] FIG. 9 is a diagram comparing heating distribution
characteristics of microwaves of 2.4 GHz and 5.8 GHz,
[0086] FIG. 10 illustrates views for explaining the high frequency
heating apparatus according to the invention, FIG. 10(a) is a
vertical sectional view showing an inner structure thereof, FIG.
10(b) shows an example of a state of arranging a feeding port
provided at a floor portion,
[0087] FIGS. 11(a) through 11(c) are perspective views showing an
evaporation bowl of a steam generating portion used in the high
frequency heating apparatus of FIG. 1,
[0088] FIG. 12 is a constitution diagram of a power source for
driving a magnetron of 5.8 GHz used by the invention,
[0089] FIG. 13 illustrates an example of applying a wide range wave
guide in a shape of a parallelepiped according to the invention to
a high frequency heating apparatus, FIG. 13(a) is a front
perspective view showing an example of applying the wave guide to a
floor portion of the high frequency heating apparatus, FIG. 13(b)
is a front perspective view showing an example of applying the wave
guide to a ceiling of the high frequency heating apparatus,
respectively,
[0090] FIG. 14 is a vertical sectional view showing an inner
structure of a high frequency heating apparatus of a first
background art,
[0091] FIG. 15 illustrates views showing an inner structure of a
high frequency heating apparatus of a second background art, FIG.
15(a) is a vertical sectional view, FIG. 15(b) is a cross-sectional
view passing a wave guide 53 of FIG. 15(a),
[0092] FIG. 16 is a conceptual constitution view of a high
frequency heating apparatus according to the invention,
[0093] FIG. 17 is a constitution diagram of a high frequency
driving portion of a high frequency heating apparatus,
[0094] FIG. 18 is a perspective view of an outlook of a high
frequency heating apparatus for explaining a choke for preventing
leakage of radio wave,
[0095] FIG. 19 illustrates sectional views showing a section (a)
taken along a line A-A of FIG. 3 and a sectional view showing a
section (b) taken along a line B-B thereof,
[0096] FIG. 20 is a perspective view of a choke,
[0097] FIG. 21 illustrates a partial outline section of a high
frequency heating apparatus for explaining a stirrer blade,
[0098] FIG. 22 illustrates outline sectional views of a high
frequency heating apparatus, FIG. 22(a) is an explanatory view
showing upper feeding of a high frequency wave of 2.45 GHz, FIG.
22(b) is an explanatory view showing side feeding thereof,
[0099] FIG. 23 shows a state of a standing wave at a certain moment
appeared in a heating chamber, FIG. 23(a) is an explanatory view
showing a high frequency wave of 2.45 GHz, FIG. 23(b) is an
explanatory view showing a high frequency wave of 5.8 GHz, FIG.
23(c) is an explanatory view showing a wave synthesized with high
frequency waves of 2.45 GHz and 5.45 GHz,
[0100] FIG. 24 is a conceptual sectional constitution view of a
high frequency heating apparatus dividing a heating chamber upward
and downward by a partition plate,
[0101] FIG. 25 is a sectional view of a partition plate,
[0102] FIG. 26 is a constitution diagram showing other constitution
example of a high frequency driving portion,
[0103] FIG. 27 is an explanatory view showing patterns for feeding
electricity to a first high frequency generating portion, a second
high frequency generating portion and showing patterns of
alternately outputting high frequency waves of 5.8 GHz and 2.45
GHz,
[0104] FIG. 28 is an explanatory view showing patterns of feeding
electricity to a first high frequency generating portion, a second
high frequency generating portion, and showing patterns of
simultaneously outputting high frequency waves of 5.8 GHz and 2.45
GHz,
[0105] FIG. 29 is an explanatory view showing patterns of feeding
electricity to a first high frequency generating portion, a second
high frequency generating portion and showing patterns of
precedingly outputting a high frequency wave of 2.45 GHz and
succeedingly outputting a high frequency wave of 5.8 GHz,
[0106] FIG. 30 is an explanatory view showing a pattern of feeding
electricity to a first high frequency generating portion, a second
high frequency generating portion, and showing a pattern of
outputting only a high frequency wave of 5.8 GHZ.
[0107] Further, in notations in the drawings, numeral 1 designates
a high frequency heating apparatus, numeral 2 designates a heating
chamber, numeral 3 designates a cavity, notation 3a designates an
upper wall, notation 3b designates a rear wall (side wall),
notation 3c designates a bottom wall, numeral 5 designates a
magnetron, numerals 7, 9 designate feeding ports, notations 7a, 7b,
7c designate feeding ports, numeral 11 designates a wave guide,
notations 11a, 11b, 11c designate wave guides, numeral 13
designates an outer shell cabinet, numeral 15 designates a front
opening/closing door, numerals 21, 31, 41 designate high frequency
heating apparatus, numeral 43 designates a face heater, numerals
51, 61 designate high frequency heating apparatus, numeral 110
designates a high frequency heating apparatus according to the
invention, numeral 111 designates a heating chamber, notation 111a
designates a ceiling of a heating chamber, notation 111b designates
a side wall of a heating chamber, notation 111c designates a floor
portion, numeral 112 designates a high frequency generating
portion, numeral 113 designates a wave guide, notation 113
designates a feeding port, numeral 117 designates a door, numeral
118 designates radio wave leakage preventing means, numeral 131
designates a commercial power source, numeral 132 designates a
magnetron, numeral 133 designates a rectifier circuit, numeral 134
designates a choke coil, numeral 135 designates a smoothing
capacitor, numeral 136 designates an inverter, numeral 1361
designates an inverter control circuit, numeral 1362 designates a
thermistor, numeral 138 designates a step-up transformer, numeral
1381 designates a primary winding, numeral 1382 designates a
secondary winding, numeral 1383 designates a filament heating
winding, numeral 139 designates a single rectifier circuit, numeral
140 designates a heating cooker, numeral 141 designates a heating
chamber, notation 141a designates a ceiling, notation 141b
designates a side wall, notation 141c designates a floor portion,
numeral 143 designates a high frequency generating portion, numeral
144 designates a wide range wave guide in a shape of a
parallelepiped arranged on a floor side, numeral 145 designates a
feeding port, numeral 146 designates a wide range wave guide in a
shape of a parallelepiped arranged on a side of a ceiling, numeral
147 designates a feeding port, numeral 211 designates a heating
chamber, numeral 213 designates a first high frequency generating
portion, numeral 215 designates a second high frequency generating
portion, numeral 217 designates a high frequency driving portion,
numeral 219 designates a control portion, numeral 225 designates a
magnetron (for 2.45 GHz), numeral 227 designates a lower side
feeding port, numeral 229 designates a lower side wave guide,
numeral 231 designates a magnetron (for 5.8 GHz), numeral 233
designates an upper side feeding port, numeral 235 designates an
upper side wave guide, numeral 237 designates a first inverter
circuit, numeral 267 designates a second inverter circuit, numeral
273 designates a drive control portion, numeral 275 designates an
opening/closing door, numeral 277 designates a heating chamber main
body, numeral 279 designates a choke, numeral 281 designates a
conductor piece, numeral 283 designates a metal plate, numeral 285
designates a groove, numeral 297 designates a partition plate,
numerals 2100, 2200 designate high frequency heating apparatus,
numeral 2109 designates a change over switch, numeral 2111
designates a drive control portion, notation M designates a heated
object.
BEST MODE FOR CARRYING OUT THE INVENTION
[0108] A detailed explanation will be given of a high frequency
heating apparatus according to preferable embodiments of the
invention in reference to the drawings as follows.
[0109] FIG. 1 is a sectional view according to a first embodiment
of a high frequency heating apparatus according to the
invention.
[0110] The high frequency heating apparatus 1 according to the
first embodiment can be used as a household microwave oven and is
constructed by a constitution including the cavity 3 for
partitioning the heating chamber 2, the magnetron 5 which is high
frequency generating means for outputting a microwave of 5.8 GHz
from an antenna 5a, a plurality of pieces of the wave guides 11a,
11b respectively having the feeding ports 7, 9 for guiding the
microwave outputted from the antenna 5a to emit to the heating
chamber 2, the outer shell cabinet 13 for ensuring a space of
installing the magnetron 5 and the wave guides 11a, 11b at a
surrounding of the cavity 3 by surrounding an outer surrounding of
the cavity 3, and the front opening/closing door 15 for
opening/closing a front face of the heating chamber 2 for bringing
a heated object to and from the heating chamber 2.
[0111] FIG. 1 is a sectional view in a state of viewing the
apparatus from a right side, a left end face of the drawing is the
front face of the apparatus, and a lower end face of the drawing is
a bottom face of the apparatus.
[0112] According to the first embodiment, the magnetron 5 is
mounted to an outer face of the rear wall 3b of the cavity 3, the
first wave guide 11a is mounted along the upper wall 3a of the
cavity 3 constituting an upper face of the heating chamber 2 by
being extended upward from the magnetron 5, and the feeding port 7
is opened at substantially a center of the upper wall 3a. Further,
the second wave guide 11b is mounted by being extended downward
from the magnetron 5, and the feeding port 9 is opened at a
position proximate to a lower end of the rear wall 3b of the cavity
3 constituting a rear face of the heating chamber 2.
[0113] According to the high frequency heating apparatus 1
constituted in this way, the microwaves are emitted from the
respective feeding ports 7, 9 of the respective wave guides 11a,
11b and therefore, a distribution of heating spots by the
microwaves can be widened and the microwaves are made to impinge on
a portion of a wider range of a surface of the heated object.
[0114] As a result, a substantial baking depth can be increased by
heating the heated object even by the microwaves of 5.8 GHz having
a shallow baking depth from two directions of the heating chamber
orthogonal to each other, and an irregularity in heating can be
restrained from being brought about over entire regions of a
surface layer and an inner deep portion of the heated object
without mounting electromagnetic wave stirring means of a turn
table, a stirrer fan or the like in the heating chamber 2.
[0115] Therefore, even with regard to a thick-walled heated object,
excellent heating without an irregularity in heating can be
realized, further, by deleting electromagnetic stirring means,
simplification of the structure, small-sized formation of the
apparatus in accordance therewith, or a reduction in fabrication
cost or running cost can be achieved.
[0116] Further, in order to compensate for a drawback that the
baking depth of the microwave of 5.8 GHz is shallow, from a view
point of increasing faces on the heated object on which the
microwaves are made to impinge, in arranging the feeding ports for
emitting the microwaves, the feeding ports may be mounted
dispersingly on a plurality of inner wall faces of the cavity 3,
and the arrangement is not limited to that in the above-described
embodiment. Further, also a number of mounting the wave guides is
not limited to two pieces according to the above-described
embodiment. The number can be increased to an arbitrary number of 3
pieces or more.
[0117] Specifically, the positions of mounting the feeding ports
can be disposed at upper and lower faces of the heating chamber 2,
or an upper face and a side face (including a rear face) thereof,
or a side face (including a rear face) and a lower face.
[0118] FIG. 2 is a sectional view of a second embodiment of the
high frequency heating apparatus according to the invention.
[0119] The high frequency heating apparatus 21 of the second
embodiment is constructed by a constitution in which the wave
guides 11a, 11b are arranged such that the two feeding ports 7, 9
are opened at upper and lower faces of the heating chamber 2, that
is, to be opposed to the upper wall 3a and the bottom wall 3c of
the cavity 3, although the first wave guide 11a is the same as that
of the first embodiment, the second wave guide 11b is mounted along
the bottom wall 3c of the cavity 3 constituting the lower face of
the heating chamber 2 by being extended downward from the magnetron
5 and the feeding port 9 is opened at substantially a center of the
bottom wall 3c.
[0120] Further, the second embodiment is constructed by the
constitution common to that of the first embodiment other than a
change in the positions of mounting the feeding ports 7, 9 and a
change in shapes of the wave guides 11a, 11b in accordance
therewith and therefore, the common constitution is attached with
the same numeral and an explanation thereof will be omitted.
[0121] According to the constitution of opposedly arranging the
feeding ports 7, 9 at wall faces of the cavity 3 opposed to each
other in this way, the substantial baking depth can be increased
even by the microwaves of 5.8 GHz having the shallow baking depth
by heating the heated object respectively from two directions
opposed to each other, even when electromagnetic wave stirring
means of a turn table, a stirrer fan or the like is not mounted in
the heating chamber 2, an irregularity in heating can be restrained
from being brought about over entire regions of the surface layer
and the inner depth portion of the heated object, similar to the
first embodiment, excellent heating without an irregularity in
heating can be realized even for the thick-walled heated object,
further, by deleting electromagnetic wave stirring means,
simplification of the structure and small-sized formation of the
apparatus in accordance therewith, or a reduction in fabrication
cost or running cost can be achieved.
[0122] FIG. 3 is a perspective view of a third embodiment of the
high frequency heating apparatus according to the invention viewed
from a rear side.
[0123] The high frequency heating apparatus 31 of the third
embodiment is constructed by a constitution of providing two pieces
of the feeding ports 7a, 7b at the upper face of the heating
chamber 2 by two pieces of the wave guides 11a, 11b arranged at the
upper wall 3a of the cavity 3. Two pieces of the wave guides 11a,
11b are formed by bifurcating a single piece of the common tube 11
extended upward from the magnetron 5.
[0124] According to the constitution, impingement of the microwaves
from the upper face to the heated object contained in the heating
chamber 2 can uniformly be dispersed over a wide range and it can
be expected to considerably increase a heating distribution to the
upper face of the heated object.
[0125] Further, by combining a constitution of providing a feeding
port at a side face (including rear face) or a bottom face of the
heating chamber 2 to the constitution of mounting two pieces of the
feeding ports 7a, 7b to the upper face of the heating chamber 2 as
in FIG. 3, a performance of uniformly heating the heated object can
further be promoted.
[0126] Further, FIG. 4(a) is a cross-sectional view of a wave guide
for guiding a microwave of 2.45 GHz, and FIG. 4(b) is a
cross-sectional view of a wave guide for guiding a microwave of 5.8
GHz. The respective cross-sectional views are drawn by the same
contraction scale.
[0127] As illustrated, a cross-sectional area of the wave guide for
guiding the microwave of 5.8 GHz is contracted to about 1/4 of a
cross-sectional area of the wave guide for guiding the microwave of
2.45 GHz. Therefore, a long side dimension b2 of the wave guide for
5.8 GHZ becomes substantially the same as a short side dimension a1
of the wave guide for 2.45 GHz.
[0128] FIG. 5 is a perspective view of a fourth embodiment of the
high frequency heating apparatus according to the invention viewed
from a rear side.
[0129] The high frequency heating apparatus 41 of the fourth
embodiment is constituted by further improving the high frequency
heating apparatus 31 shown in FIG. 3 in consideration of the
dimensional difference between the wave guides shown in FIG. 4, two
pieces of the wave guides 11a, 11b arranged at the upper wall 3a of
the cavity 3 are mounted by a vertical arrangement in which the
long side b2 of a cross-sectional face of the wave guide is
directed in an up and down direction, further, the face heater 43
is arranged at a region of the upper wall 3a of the cavity 3
excluding a region of mounting the wave guides arranged
vertically.
[0130] When the frequency of the microwave used is 5.8 GHz, in this
way, even when the wave guides 11a, 11b arranged at the upper wall
3a of the cavity 3 are vertically arranged, as shown by FIG. 6, a
space L of installing the wave guides ensured on the upper face
side of the cavity 3 can be set to be equivalent to that of the
high frequency heating apparatus of the background art in which the
wave guide for 2.45 GHz is installed to the upper face of the
cavity 3 by directing the long side horizontally. Further, by
vertically arranging the wave guide, by reducing an occupied area
of the wave guide at the upper wall 3a of the cavity 3 in a width
direction, the occupied area can be reduced.
[0131] As a result, a vacant area of the upper wall 3a of the
cavity 3 is increased and as shown by FIG. 5, there can be
constructed a constitution of arranging the face heater 43 over an
entire region of a large vacant region of the upper wall 3a of the
cavity 3 excluding a region of mounting the wave guides 11a,
11b.
[0132] That is, the face heater 43 can be mounted by a larger area,
and oven heating without an irregularity in heating can be realized
by making a temperature distribution in an oven heating processing
by operating the face heater 43 uniform over a wider region.
[0133] Further, the position of vertically arranging the wave guide
as described above is not limited to the upper wall 3a of the
cavity 3.
[0134] FIGS. 7(a) and (b) are sectional views of a fifth embodiment
of the high frequency heating apparatus according to the invention.
Further, FIGS. 7(a) and (b) show examples of different heating
distributions in the heating chamber by electric lines of
force.
[0135] According to the high frequency heating apparatus 51 of the
fifth embodiment, in the constitution of arranging two pieces of
the wave guides 11a, 11b opposedly to upper and lower faces of the
heating chamber 2 as previously shown in FIG. 2, the wave guides
11a, 11b are respectively set to be arranged vertically.
[0136] According to the constitution, microwaves irradiated from
the respective feeding ports 7, 9 opposed to each other upward and
downward form standing waves phases of which are shifted from each
other by 180.degree. and therefore, further uniform formation of
the heating distribution with regard to the heated object can be
expected.
[0137] Describing further, by shifting the phases of the microwaves
irradiated from the respective upward and downward feeding ports 7,
9 by 180.degree., both of the microwaves can align a direction of
an electric field in one direction. Thereby, as shown by FIGS. 7(a)
and (b), heating of the heated object can be promoted by an
electric field intensity constituted by adding those of both
electric fields. Further, as shown by FIG. 7(b), more microwave
energy can be transmitted to an inner portion of a food
product.
[0138] Further, although it is difficult to arbitrarily selecting
FIGS. 7(a) and (b) in accordance with the heated object, it can be
expected that either of FIGS. 7(a) and (b) is brought about as a
change over time in accordance with progress of heating of the
heated object and therefore, uniform formation of heating can be
promoted.
[0139] Further, when the cavity 3 is mounted with a plurality of
pieces of the wave guides, the mounting number is not limited to
two pieces shown in the above-described embodiment but can be
improved to an arbitrary number.
[0140] FIG. 8 is a plane view of an upper face of the cavity of a
sixth embodiment of the high frequency heating apparatus according
to the invention.
[0141] The high frequency heating apparatus 61 is mounted with
three pieces of the feeding ports 7a, 7b, 7c by the trifurcated
wave guides 11a, 11b, 11c at the upper wall 3a of the cavity 3,
further, according to three pieces of the feeding ports 7a, 7b, 7c,
a position of the center feeding port 7b is shifted from those of
the other feeding ports 7a, 7c. Further, the center wave guides 11b
is narrowed at a branch base portion 12 into a mode of contracting
a cross-sectional area in comparison with those of the other wave
guides 11a, 11c. Further, all of three pieces of the wave guides
are arranged vertically.
[0142] Thereby, irradiation of the microwaves from the upper face
of the heating chamber 2 can further uniformly be diffused over a
wide region of the heating chamber 2 by a high density and an
irregularity in heating with regard to the heated object can
further be prevented. Further, the reason of narrowing the center
wave guide 11b is that the center wave guide 11b is linearly
extended from the magnetron 5 and an efficiency of guiding the
microwave is higher than those of the wave guides 11a, 11c and
therefore, the center wave guide 11b is balanced with the other
wave guides 11a, 11c by restricting the efficiency.
[0143] A detailed explanation will be given of a seventh embodiment
of the invention as follows.
[0144] FIG. 10 illustrates views for explaining the high frequency
heating apparatus according to the invention, FIG. 10(a) is a
vertical sectional view showing an inner structure thereof, FIG.
10(b) shows an example of a state of arranging a feeding port
provided at a floor portion.
[0145] In FIG. 10(a), numeral 110 designates the high frequency
heating apparatus according to the invention, numeral 111
designates the heating chamber, notation 111a designates the
ceiling of the heating chamber, notation 111b designates the side
wall of the heating chamber, notation 111c designates the floor
portion. The floor portion 111c comprises a material which is not a
metal, for example, ceramic. Numeral 112 designates the high
frequency generating portion provided on an outer side of a rear
side of the floor portion 111c of the heating chamber 111 for
oscillating the microwave having the frequency of 5.8 GHz, numeral
113 designates the wave guide provided on the rear side of the
floor portion 111c of the heating chamber 111 and a so-to-speak
wide range wave guide in a shape of a parallelepiped a shape of
which is constituted by a parallelepiped (for example, longitudinal
length 30 cm.times.lateral length 30 cm.times.height 5 cm). An area
of a wide face of the six faces substantially coincides with an
area of the floor portion 111c. Further, notation 113a designates a
wave guide ceiling (face opposed to the floor portion 111c),
notation 113b designates a number of feeding ports formed
substantially over an entire face of the wave guide ceiling 113a.
Numeral 117 designates the door, numeral 118 designates radio wave
leakage preventing means having a choke structure provided at four
sides of the door 117 in correspondence with a quarter wave length
of the microwave.
[0146] FIG. 10(b) shows one arrangement example of the feeding
ports formed substantially over an entire face of the wave guide
ceiling 113a. Here, each feeding port 113b is constituted by a
rectangle a long side of which is provided with a length equal to
or larger than 1/4.lamda. (about 1.3 cm) and 7 pieces thereof are
provided at a row proximate to the high frequency generating
portion 112, 8 pieces thereof are provided at a successive row and
9 pieces thereof are provided at a row remote from the high
frequency generating portion 112.
[0147] By constituting a state of arranging a number of pieces of
the feeding ports in this way, a microwave having a strong electric
field intensity proximate to the high frequency generating portion
112 is brought into the heating chamber 111 by a small amount, a
microwave having a weak electric field intensity remote from the
high frequency generating portion 112 is brought into the heating
chamber 111 by a large amount and therefore, a comparatively
uniform electric field intensity is constituted in the heating
chamber 111, which contributes to uniform heating of the heated
object G.
[0148] In contrast thereto, as shown by FIG. 15(b), the wave guide
113 of the background art is constituted by a slender pipe and is
provided with one piece of the feeding port 154 and therefore, it
is difficult to achieve a uniform electric field intensity in the
heating chamber 111 and therefore, uniform heating of the heated
object G is difficult.
[0149] Further, according to the invention, a size of a hole of the
feeding port 113b1 at the row proximate to the high frequency
generating portion 112 is made to be smaller and the size is made
to be larger in accordance with being remote from the high
frequency generating portion 112 and therefore, a microwave having
the strong electric field intensity proximate to the high frequency
generating portion 112 is brought into the heating chamber 111 by a
small amount, the microwave having the weak electric field
intensity remote from the high frequency generating portion 112 is
brought into the heating chamber 111 by a large amount and
therefore, a comparatively uniform electric field intensity is
constituted in the heating chamber 111, which contributes to
uniform heating of the heated object G.
[0150] Operation of the high frequency heating apparatus 110 is as
follows.
[0151] When the magnetron 112 is driven, a microwave having the
frequency of 5.8 GHz is oscillated from the magnetron 112. The
oscillated microwave having the frequency of 5.8 GHz is brought to
an entire face of the rear side of the floor portion 111c by
passing the wave guide 113 provided at a total of the rear side of
the floor portion 111c of the heating chamber 111, brought into the
heating chamber 111 from a number of the respective feeding ports
113b scatteringly provided at the wave guide 113, further, a number
of pieces and the sizes of holes of the feeding ports 113b are
determined unproportionally to the electric field intensity and
therefore, as a result, a uniform electric field intensity is
constituted in the heating chamber and therefore, thereby, the
heated object G is heated without an irregularity in heating.
[0152] Further, also a structure of the wave guide is simply
constituted by the parallelepiped and is solid, promotes
reliability and reduces cost.
[0153] Further, the wide range wave guide 113 in the shape of the
parallelepiped is formed at a space which is vacant in the
background art on the rear side of the floor portion and therefore,
the space can effectively be utilized and a volume of a space in
the heating chamber can be increased by an amount of a space of the
wave guide 153 provided at the ceiling of the heating chamber 151
in FIG. 15.
[0154] Further, since the feeding port is proximate to the food
product constituting the heated object, absorption of a radio wave
is improved.
[0155] Further, in the case of an microwave oven having a heater,
arrangement of an upper heater is much simplified.
[0156] FIG. 11 shows an example of other arrangement of feeding
ports provided at a ceiling of a wave guide of a wide range wave
guide in a shape of a parallelepiped.
[0157] FIG. 11(a) shows a wide range wave guide in a shape of a
parallelepiped having feeding ports arranged radially.
[0158] In the drawing, numeral 112 designates the high frequency
generating portion, numeral 113 designates the wide range wave
guide in the shape of the parallelepiped, notation 113a designates
the ceiling, notation 113b designates the feeding port opened at
the ceiling 113a, notations b1 through b3 respectively designate
holes having different sizes.
[0159] The feeding ports b1 through b3 in a shape of a long hole
are radially arranged from a center of the wave guide ceiling 113a
of the heating chamber 111. Further, as is known by comparing the
feeding ports b1 and b3, the remoter from the center, the longer
the long hole.
[0160] As a result, a uniform electric field distribution is
constituted up to a corner portion which the microwave is
comparatively difficult to reach and the heated object G is heated
without an irregularity in heating regardless of an area
thereof.
[0161] FIG. 11(b) shows a wide range wave guide in a shape of a
parallelepiped having feeding ports in an arrangement in a shape of
a checkerboard.
[0162] In the drawing, numeral 112 designates the high frequency
generating portion, numeral 113 designates the wide range wave
guide in the shape of the parallelepiped, notation 113a designates
the ceiling, notation 113b designates the feeding port opened at
the ceiling 113a, and notations b1 through b4 designate holes
respectively having different sizes.
[0163] The feeding ports b1 through b4 in a rectangular shape are
arranged in a shape of a checkerboard on the wave guide ceiling
113a of the heating chamber 111. Further, as is known by comparing
the feeding ports b1a and b4, the remoter from the wide of the high
frequency generating portion 112, the longer the side of the
feeding port.
[0164] As a result, a uniform electric field distribution is
constituted up to a portion on a side opposed to a portion of
installing the high frequency generating portion 112 and a portion
which the microwave is comparatively difficult to reach and the
heated object G is heated without an irregularity in heating
regardless of an area thereof.
[0165] FIG. 11(c) shows a wide range wave guide in a shape of a
parallelepiped having feeding ports arranged radially.
[0166] In the drawing, numeral 112 designates the high frequency
generating portion, numeral 113 designates the wide range wave
guide in the shape of the parallelepiped, notation 113a designates
the ceiling, notation 113b designates the feeding port opened at
the ceiling 113a, and notations b1 through b3 designate holes
respectively having different sizes.
[0167] The feeding ports b1 through b3 in a rectangular shape are
radially arranged from the high frequency generating portion 112 on
the wave guide ceiling 113a. Further, it is known by comparing the
feeding ports b1 and b3, the remoter from the center, the longer
the long hole.
[0168] As a result, a uniform electric field distribution is
constituted up to a portion on a side opposed to a portion of
installing the high frequency generating portion 112 and a portion
which the microwave is comparatively difficult to reach and the
heated object G is heated without an irregularity in heating
regardless of an area thereof.
[0169] FIG. 12 is a constitution diagram of a power source for
driving the magnetron of 5.8 GHz used in the invention. In the
drawing, an alternating current from the commercial power source
131 is rectified into a direct current by the rectifier circuit
133, smoothed by the choke coil 134 and the smoothing capacitor 135
on an output side of the rectifier circuit 133 and is inputted to
an input side of the inverter 136. The direct current is converted
into a desired high frequency wave (20 through 40 kHz) by ON/OFF of
a semiconductor switching element in the inverter 136. The inverter
136 is controlled by IGBT (Insulated Gate Bipolar Transistor) for
switching the direct current at high speed and the inverter control
circuit 1361 for controlling to drive the IGBT and a current
flowing on a primary side of the step-up transformer 138 is
switched ON/OFF at high speed.
[0170] As an input signal of the control circuit 1361, a primary
side current of the rectifier circuit 133 is detected by CT 137 and
the detected current is inputted to the inverter control circuit
1361 and is used to control the inverter 136. Further, a cooling
fin for cooling IGBT is attached with a temperature sensor
(thermistor) 1362 and detected temperature information by the
temperature sensor is inputted to the inverter control circuit 1361
and is used for controlling the inverter 136.
[0171] In the step-up transformer 138, the primary winding 1381 is
applied with a high frequency voltage which is an output of the
inverter 136 and a high voltage in accordance with the turn ratio
is provided at the secondary winding 1382. Further, a winding 1383
having a small turn number is provided on the secondary side of the
step-up transformer 138 and is used for heating the filament 1321
of the magnetron 132 for oscillating 5.8 GHz. The secondary winding
1382 of the step-up transformer 138 is provided with a double
voltage single way rectifier circuit 139 for rectifying an output
thereof. The double voltage single way rectifier circuit 139 is
constituted by a high voltage capacitor 1391 and two pieces of high
voltage diodes 1392, 1393.
[0172] By the circuit having the above-described constitution, the
alternating current is rectified and smoothed, converted into the
high frequency wave at the inverter, the voltage is transformed
into the high voltage at high frequency by the high voltage
transformer, thereafter, the high voltage is rectified and the
magnetron is driven. When the magnetron is driven, the microwave of
5.8 GHz is oscillated from the antenna, the microwave of 5.8 GHz is
conducted through the wide wave guide constituted by substantially
the entire face of the rear side of the floor portion of the
heating chamber and is brought into the heating chamber from the
optimum feeding port while repeating reflection at the wall face of
the wave guide.
[0173] Therefore, substantially the total of the rear side of the
floor portion constitutes the wave guide structure, a number of
pieces of the feeding ports for passing the high frequency wave
into the heating chamber are provided substantially over the total
face of the floor portion and therefore, there is not brought about
a difference in the electric field intensity of the microwave
between the center and the corner of the heating chamber to enable
to be proximate to uniform heating. Further, the wave guide is
provided on this side to be aligned with a steam generating
apparatus provided at the corner on the rear side of the floor
portion and therefore, a wasteful space is eliminated and the space
volume in the heating chamber can be increased by an amount of the
space of the rear side of the ceiling installed with the wave guide
of the background art.
[0174] By using the magnetron for oscillating the high frequency
wave having the frequency of 5.8 GHz in this way, the wavelength
becomes about 5 cm and therefore, the wavelength is smaller in
comparison with the wide range wave guide in the shape of the
parallelepiped according to the invention and therefore, the
microwave is easy to be irradiated in the wide range wave guide in
the shape of the parallelepiped, and uniform formation of heating
can be achieved by randomly distributing the microwaves.
[0175] Although in the above-described explanation, as the
magnetron used, the magnetron having the frequency of 5.8 GHz is
used, the invention is not limited thereto but the magnetron used
may be a general purpose magnetron of 2.45 GHz. However, in the
latter case, the wavelength is about 12 cm and therefore, the
wavelength is large in comparison with a size of the wide range
wave guide in the shape of the parallelepiped according to the
invention and therefore, the microwave needs to be devised to be
distributed in the wide range wave guide in the shape of the
parallelepiped.
[0176] According to the invention, the uniform formation can be
achieved by making numbers of pieces and sizes of holes of the
feeding ports depend on the distance from the magnetron and
therefore, also in the case of the magnetron of 2.45 GHz, by
carefully selecting the numbers of pieces and sizes of holes of the
feeding ports, uniform heating can be carried out.
[0177] FIG. 13 illustrates front perspective views showing an
example of applying the wide range wave guide in the shape of the
parallelepiped according to the invention to the high frequency
heating apparatus, FIG. 13(a) is a front perspective view showing
an example of applying the wide range wave guide in the shape of
the parallelepiped to the floor portion of the high frequency
heating apparatus and FIG. 13(b) is a front perspective view
showing an example of applying the wide range wave guide in the
shape of the parallelepiped to the ceiling of the high frequency
heating apparatus, respectively. In the drawings, the door is
omitted and the wide range wave guide in the shape of the
parallelepiped is shown in a state of being removed from the main
body of the heating apparatus.
[0178] In FIG. 13(a), numeral 140 designates the heating cooker for
heating to process the heated object by supplying the microwave to
the heating chamber. Numeral 141 designates the heating chamber
which is constituted by the ceiling 141a, the side wall 141b and
the floor portion 141c. Numeral 142 designates a circulating fan
for circulating air in the heating chamber 141, numeral 143
designates the high frequency generating portion including the
magnetron, numeral 144 designates the wide range wave guide in the
shape of the parallelepiped according to the invention, numeral 145
designates the feeding port.
[0179] The heating chamber 141 is formed at inside of a main body
case in a shape of a box a front face of which is opened and a
front face of the main body case is provided with an
opening/closing door (not illustrated) for opening/closing a port
of taking out the heated object. The opening/closing door is made
to be able to be opened/closed in an up and down direction by
coupling a lower end to a lower edge of the main body case by a
hinge.
[0180] A size of the wide range wave guide 144 in the shape of the
parallelepiped is constituted by a size equal to substantially a
total face of the floor portion 141 according to the invention. The
wave guide of the background art is constituted by a slender pipe
the section of which is rectangular and the width of which is equal
to the width of the high frequency generating portion and is
provided with a single piece of the feeding port and therefore, it
is difficult to achieve the uniform electric field intensity in the
heating chamber and therefore, uniform heating of the heated object
G is difficult, however, according to the wide range wave guide 144
in the shape of the parallelepiped, a large number of the feeding
ports 145 are scattered on the floor side, the size is smaller at
the vicinity of the high frequency generating portion 143, the
remoter from the high frequency generating portion 143, the larger
the size and therefore, the heated object placed at the floor
portion is heated thermally efficiently and can be heated
uniformly.
[0181] Further, by arranging the wide range wave guide 113 in the
shape of the parallelepiped particularly at the floor portion, a
space volume in the heating chamber can be increased, further, the
feeding port becomes proximate to the food product which is the
heated object and therefore, absorption of radio wave is improved.
Further, in the case of a model of an microwave oven having a
heater, there is also achieved an effect of much simplifying
arrangement of an upper heater.
[0182] In FIG. 13(b), numeral 140 similarly designates the heating
cooker, numeral 141 designates the heating chamber, numeral 142
designates the circulating fan, numeral 143 designates the high
frequency generating portion, numeral 146 designates the wide range
wave guide in the shape of the parallelepiped, numeral 147
designates the feeding port.
[0183] The size of the wide range wave guide 146 in the shape of
the parallelepiped is constituted by a size substantially equal to
a total face of the ceiling 141a according to the invention, a
large number of the feeding ports 147 are scattered on the ceiling
side, the size is smaller at the vicinity of the high frequency
generating portion 143, the remoter from the high frequency
generating portion 143, the larger the size and therefore, uniform
radio waves fall from the single face of the ceiling as in the
shower and therefore, further uniform heating can be carried
out.
[0184] Further, by arranging the wide range wave guide 113 in the
shape of the parallelepiped particularly at the ceiling, a
sufficient space can be produced below the floor and therefore,
when a food product is automatically heated, a weight sensor for
detecting a weight of the food product is easy to be arranged,
further, in the case of a model of using a turn table, the turn
table can simply be constituted.
[0185] A detailed explanation will be given of a preferable
embodiment of a high frequency heating apparatus and its control
method according to the invention as an eighth embodiment in
reference to the drawing as follows.
[0186] FIG. 16 is a conceptual constitution diagram of the high
frequency heating apparatus according to the invention, and FIG. 17
is a constitution diagram of a high frequency driving portion of
the high frequency heating apparatus.
[0187] As shown by FIG. 16, the high frequency heating apparatus
2100 heats to process the heated object M by supplying the high
frequency wave to the heating chamber 211 containing the heated
object M and is provided with the first high frequency generating
portion 213 for generating the high frequency wave having the
frequency of 2.45 GHz and the second high frequency generating
portion 215 for generating the high frequency wave having the
frequency of 5.8 GHz. Further, the high frequency heating apparatus
2100 is provided with the high frequency driving portion 217, the
control portion 219 for driving to oscillate the first and the
second high frequency generating portions, and the control portion
219 is connected with an input operating portion 221 of a start
switch for instructing to start heating, a menu switch for setting
content of heating and the like, and a display portion 223 for
displaying various information. The control portion 219 heats the
heated object M on a mounting base 220 under a desired condition by
controlling to drive the high frequency generating portions based
on an input content from the input operating portion 221.
[0188] The first high frequency generating portion 213 includes the
magnetron 225 for oscillating the high frequency wave having the
frequency of 2.45 GHz, and the lower side wave guide 229 for
guiding the high frequency wave outputted from an antenna 225a of
the magnetron 225 to the lower side feeding port 227 provided on
the bottom face side of the heating chamber 211.
[0189] Further, similarly, the second high frequency generating
portion 215 includes the magnetron 231 for oscillating the high
frequency wave having the frequency of 5.8 GHz, and the upper side
wave guide 235 for guiding the high frequency wave outputted from
an antenna 231a of the magnetron 231 to the upper side feeding port
233 provided on an upper face side of the heating chamber 211.
[0190] The high frequency driving portion 217 is provided with the
inverter circuit for individually driving the respective magnetrons
225, 231 as shown by an example in FIG. 17. The first inverter
circuit 237 for driving the magnetron 225 is supplied with a power
from a commercial power source 249 by being subjected to full-wave
rectification by a rectifier circuit 251 of a diode bridge or the
like, converts the power into a high frequency voltage and
thereafter supplies the high frequency voltage to a primary winding
255 of a step-up transformer 253. Then, a high voltage having a
high frequency of several kV is generated at a secondary winding
257 of the step-up transformer 253. Further, the high voltage
having the high frequency is rectified by a double voltage
rectifier circuit 261 comprising a capacitor 258 and a diode 259
and the magnetron 225 is applied with the high voltage. Further, a
heater winding 263 of the step-up transformer 253 is connected to a
filament 265 of the magnetron 225 to heat the filament 265.
Further, the magnetron 225 oscillates the high frequency by being
heated by the filament 265 and applied with the high voltage.
[0191] The respective constitutions of the first inverter circuit
237, the step-up transformer 253 and the double voltage rectifier
circuit 261 for driving the magnetron 225 are similar to
constitutions of the second inverter circuit 267, a step-up
transformer 269, and a double voltage rectifier circuit 271 for
driving the magnetron 231 and therefore, portions having the same
functions are attached with the same notations to thereby omit the
explanation.
[0192] Further, the first inverter circuit 237 and the second
inverter circuit 267 are connected with the drive control portion
273 and the drive control portion 273 controls drive timings and a
power feeding distribution or the of the both circuits by receiving
a control signal from the control portion 219.
[0193] Here, an explanation will be given of a choke for preventing
leakage of radio wave with regard to the high frequency waves
having two kinds of the frequencies supplied to the heating chamber
211.
[0194] FIG. 18 shows a perspective view of an outlook of the high
frequency heating apparatus 2100. The heating chamber 211 in a
shape of a box is constructed by a constitution of being opened by
the opening/closing door 275 openably/closably attached to a front
face side constituting a side face of the high frequency heating
apparatus 2100 and enabling to bring the heated object to and from
the heating chamber 211 via the opening portion. That is, according
to the heating chamber 211, the heating chamber main body 277
having the opening portion is made to be openable/closable by the
opening/closing door 275 and therefore, the choke 279 for
preventing leakage of radio wave of the opening/closing door 275 is
provided at a portion of the opening/closing door 275 opposed to
the heating chamber main body 277. The choke 279 may be formed at a
portion on the side of the heating chamber main body 277 opposed to
the opening/closing door 275.
[0195] Here, FIG. 19 illustrates a section 19(a) taken along a line
A-A of FIG. 18 and a section 19(b) taken along a line B-B of FIG.
18 and FIG. 20 shows a perspective view of the choke. With regard
to a shape of the choke 279, the shape is constructed by a
constitution substantially similar to that of a choke described in
Japanese Patent No. 1504201 although frequencies thereof differ
from each other. That is, as shown by FIG. 19(a), a base end side
wall face 287 is formed by forming the groove 285 by folding at an
end portion of the metal plate 283 forming the opening/closing door
275 and by further folding a front end of the metal plate 283 in a
U-like shape, wall faces of an opened portion side groove 285a
having a groove width of b1 and a shortcircuit side groove 285b
having a groove width of b2 are formed. Further, as shown by FIG.
20, there are formed a plurality of the conductor pieces 281a by
constituting lead wire widths by a1, a3 on a side of the opened
portion side groove 285a, and constituting lead wire widths by a2,
a4 on a side of the shortcircuit side groove 285b.
[0196] Further, at the section taken along the line B-B of Fib.
19(b), a plurality of conductor pieces 281b having a shape similar
to that of the conductor piece 281a are formed by constituting a
groove width by b3 on the side of the opened hole portion side
groove 285a and constituting the groove width by b4 on the side of
the shortcircuit side groove 285b.
[0197] The conductor pieces 281a, 281b are contained alternately in
the groove 285, an opened hole end of the groove 285 is covered by
a groove cover 289, further, an outer side of the opening/closing
door 275 is covered by a door cover 291. According to the choke 279
having the above-described constitution, a ratio K1 of a
characteristic impedance of the groove shown by the section A-A is
represented by Equation (1). ( Equation .times. .times. 1 ) .times.
.times. .times. K 1 = a 1 b 2 .times. eff .times. .times. 1 a 2 b 3
( 1 ) ##EQU1##
[0198] Further, a ratio K2 of a characteristic impedance of the
groove shown by the section B-B is represented by Equation (2). (
Equation .times. .times. 2 ) .times. .times. .times. K 2 = a 3 b 4
.times. eff .times. .times. 2 a 4 b 3 ( 2 ) ##EQU2##
[0199] Respective values of K1, K2, mentioned above, are
respectively set such that depths (L1+L2) and (L3+L4) of the
grooves become the same. Further, notations .di-elect cons. eff1,
.di-elect cons.eff2 designate effective dielectric constants of the
respective groove portions.
[0200] Here, a characteristic impedance, a length, a phase constant
of the groove opened hole portion side groove are designated by
notations ZO1, L1, .beta.1 and a characteristic impedance, a
length, a phase constant of the groove shortcircuit portion side
groove are designated by notations ZO2, L2, .beta.2. Further, when
a distance from an opened hole end to a shortcircuit end of the
groove (depth of groove) is designated by notation L (total), L
(total)=L1+L2. An impedance Z at the opened hole end of the groove
is represented by Equation (3) under the above-described condition.
( Equation .times. .times. 3 ) .times. .times. .times. Z = jZ o
.times. .times. 1 tan .times. .times. .beta. 1 .times. L 1 + K
.times. .times. tan .times. .times. .beta. 2 .times. L 2 1 - K
.times. .times. tan .times. .times. .beta. 1 .times. L 1 tan
.times. .times. .beta. 2 .times. L 2 ( 3 ) ##EQU3## where
K=ZO2/ZO1
[0201] According to the embodiment, the characteristic impedances
are constituted by ZO2.noteq.ZO1 and therefore, the Equation (3),
the value of the ratio K of the characteristic impedances becomes
K.noteq.1. In order to make the impedance Z at the opened hole end
of the groove infinitive, a denominator of Equation (3) may be
nullified and therefore, 1=K tan .beta.1L1tan .beta.2L2 may be
satisfied. Therefore, since the values of K1, K2 can arbitrarily be
set by adjusting a1, a2, a3, a4 and b1, b2, b3, b4 and therefore,
by pertinently setting K1, K2, the single groove can be provided
with a seal effect for two kinds of frequencies of 2.45 GHz and 5.8
GHz.
[0202] That is, the value of the characteristic impedance ratio K
is determined such that the depth (L3+L4) of the groove for the
high frequency wave of 5.8 GHz and the depth (L1+L2) of the groove
for the high frequency of 2.45 GHz become the same. For example,
based on the characteristic impedance ratio K1 for 2.45 GHz, the
depth (L1+L2) of the groove is determined and the value of the
characteristic impedance ratio K2 for 5.8 GHz is determined to
coincide therewith. For example, when a thickness of the
opening/closing door is made to be about 20 mm, by constituting a
combination of K1>1, K2<1, there can be constituted the
groove for preventing leakage of radio wave effectively operated
for two kinds of the high frequency waves of 2.45 GHz and 5.8
GHz.
[0203] As described above, according to the constitution of the
choke of the embodiment, one or more of the grooves are provided at
at least one of portions of the heating chamber main body 277 and
the opening/closing door 275 opposed to each other, at least one
wall face of the groove is constituted by a group of the conductor
pieces continuously aligned at intervals in a longitudinal
direction of the groove and in parallel with the wall face of the
groove, a lead wire path is constituted by arranging the conductor
pieces such that the groove width is periodically changed, and by
periodically changing the ratio of the characteristic impedance of
the opening portion of the groove to the characteristic impedance
of the shortciruict end portion of the groove by changing at least
one of the dielectric constant, the lead wire path width, the
groove width in the groove, the high frequency waves having the two
different frequencies can simultaneously be shielded.
[0204] According to the constitution of the high frequency heating
apparatus explained above, as shown by an outline section of a
portion of the high frequency heating apparatus in FIG. 21, there
may be constructed a constitution in which a stirrer blade 293 for
stirring radio wave is provided at a vicinity of the lower side
feeding port of the wave guide 229 as needed, and radio wave
applied to the heating chamber 211 is forcibly stirred by driving
to rotate the stirrer blade 293 to thereby achieve further uniform
heating.
[0205] Further, as shown by an outline sectional view of the high
frequency heating apparatus in FIG. 22, there may be constructed a
constitution in which a turn table 295 axially supported rotatably
by the bottom face of the heating chamber 211 to achieve uniform
heating. In this case, there may be constructed a constitution in
which the first high frequency generating portion 213 is arranged
on the upper side of the heating chamber 211 along with the second
high frequency generating portion 215 and the high frequency wave
is supplied into the heating chamber 211 from a vicinity of the
upper side feeding port 233 of the second high frequency generating
portion 215 (refer to FIG. 22(a)), further, there may be
constructed a constitution in which the first high frequency
generating portion 213 is provided at the side face of the heating
chamber 11 and the high frequency is supplied into the heating
chamber 211 from the side face (refer to FIG. 22(b)).
[0206] Next, operation of the high frequency heating apparatus 2100
according to the invention will be explained.
[0207] When the heated object M is heated to process by using the
high frequency heating apparatus 2100 of the invention, the heating
chamber 211 is individually or simultaneously supplied with at
least either one of the high frequency wave of 2.45 GHz from the
first high frequency generating portion 213 and the high frequency
wave of 5.8 GHz from the second high frequency generating portion
215.
[0208] FIG. 23 shows a state of a standing wave at a certain moment
appeared in the heating chamber 211 as an example. FIG. 23(a) shows
the high frequency wave of 2.45 GHz, FIG. 23(b) shows the high
frequency wave of 5.8 GHz, and FIG. 23(c) shows a synthesized wave
of the high frequency waves of 2.45 GHz and 5.45 GHz.
[0209] In the case of the high frequency wave of 2.45 GHz shown in
FIG. 23(a), an interval of portions of antinodes of an electric
field at which the heating amount is increased (interval of heating
spots) becomes about 6 cm, and for the heated object M having a
length of, for example, 30 cm, portions of antinodes of a standing
wave can be included by only about 5 points on a straight line.
Therefore, an irregularity in heating is liable to be brought about
in the heated object M by producing a significant difference
between temperature elevating characteristics at a position of the
heating spots and a position other than the heating spot.
[0210] On the other hand, in the case of the high frequency wave of
5.8 GHz shown in FIG. 23(b), the interval between the heating spots
becomes about 2.6 cm and according to the above-described length,
heating spots of 10 points or more can be included in the heated
object M on a straight line. Therefore, the heated object M is
uniformly heated and an irregularity in heating by the location of
the heated object M is difficult to be brought about.
[0211] However, according to the high frequency wave of 5.8 GHz, an
absorption depth for the heated object M tends to be shallowed, and
whereas the absorption depth of the high frequency wave of 2.45 GHz
is about 5 through 7 cm from the surface of the heated object M,
according to the high frequency wave of 5.8 GHz, the absorption
depth is shallowed to about 2 through 3 cm from the surface.
Therefore, when the heated object M is heated by using only the
high frequency wave of 5.8 GHz, although the high frequency wave of
5.8 GHz will do when the heated object M is thin-walled, when the
heated object M is thick-walled, a temperature difference between
the inner portion and the surface of the heated object M is
increased and an irregularity in heating is liable to be brought
about.
[0212] Hence, as shown by FIG. 23(c), by simultaneously supplying
the high frequency wave of 2.45 GHz and the high frequency wave of
5.8 GHz, even when the heated object M is thick-walled, uniform
heating can be realized by restraining an irregularity in heating
to be small. That is, when the high frequency wave of 2.45 GHz and
the high frequency wave of 5.8 GHz are superposed, a heating effect
is achieved by increasing a bias even at a portion of a valley of a
standing wave at which the heating amount is reduced, thereby,
uniform formation of the heat effect of the high frequency wave is
achieved and uniform heating without depending on the location or
the thickness of the heated object M can be realized.
[0213] The characteristics of the respective high frequency waves
and differences of the heating effects thereby are summarized and
shown in Table 1. TABLE-US-00001 TABLE 1 2.45 GHz 5.8 GHz 2.45 GHz
+ 5.8 GHz heating distribution surface Good Excellent Excellent
characteristic of heated inner Excellent Good Excellent object
portion radio wave invasion depth 5 through 7 cm 2 through 3 cm 2
through 7 cm from surface from surface from surface interval of
heating point about 6 cm about 2.6 cm about 2.6 cm
[0214] With regard to the heating distribution characteristic of
the heated object M, whereas the high frequency of 5.8 GHz can
preferably be utilized in heating pizza, sliced meat product or the
like in a large surface area and an irregularity in heating can be
restrained from being brought about, in the case of the high
frequency of 2.45 GHz, an irregularity in heating is liable to be
brought about since the heating points are few. However, by
combining the high frequency wave of 2.45 GHz with the high
frequency wave of 5.8 GHz, uniform heating can be realized even
when a thin-walled product. Further, the high frequency wave of
2.45 GHz is more advantageous for the thick-walled heated object,
in the case of the high frequency wave of 5.8 GHz, heat does not
permeate to the inner portion of the heated object to constitute
heating by heat conduction from the surface and a heating time
period tends to be prolonged, however, by combining the high
frequency wave of 5.8 GHz with the high frequency wave of 2.45 GHz,
also the inner portion of the heated object can swiftly be
heated.
[0215] Further, even when the high frequency wave of 2.45 GHz and
the high frequency wave of 5.8 GHz are alternately switched to
supply, substantially the similar effect can be achieved.
[0216] As described above, by using the high frequencies having
different frequencies and adjusting a distribution of respective
powers, various modes of standing wave distributions can be formed
and heating having a small irregularity in heating, further, a
local heating processing can be realized.
[0217] Next, a ninth embodiment of the high frequency heating
apparatus according to the invention will be explained.
[0218] FIG. 24 shows a conceptual sectional constitution view of
the high frequency heating apparatus of the embodiment. Further,
members having functions the same as those of the constitution of
the eighth embodiment, mentioned above, are attached with the same
notations to thereby omit the explanation.
[0219] As shown by FIG. 24, the high frequency heating apparatus
2200 of the embodiment is constructed by a constitution in which
the high frequency wave of 2.45 GHz from the first high frequency
generating portion 213 is supplied from the lower side of the
heating chamber 211 and the high frequency wave of 5.8 GHz from the
second high frequency generating portion 215 is supplied from the
upper side of the heating chamber 211, and the partition plate 297
for dividing upward and downward the space of the heating chamber
211 is provided at a position of a distance h from the upper face
of the heating chamber 211 relative to a total height H of the
heating chamber 211.
[0220] The partition plate 297 is made to be attachable and
detachable to and from the heating chamber 211 easily at a
plurality of height positions, and is attached thereto by being
supported by a locking portion 299 formed at a wall face of the
heating chamber 211. As is shown by a sectional view of the
partition plate in FIG. 25, the partition plate 297 includes a
metal plate 2101 constituting a face of mounting the heated object,
a high frequency heat generating member 2103 arranged to be opposed
to or brought into contact with the metal plate 2101, and a fixing
member 2105 for fixing the high frequency heat generating member
2103 to the metal plate 2101 and engaged with the locking portion
299 on the side of the heating chamber 211.
[0221] The metal plate 2101 comprises an aluminum-plated steel
plate and is provided with recesses and projections in a wavy shape
at a surface thereof by forming the recesses and projections by
constituting the metal plate 2101 per se by a wavy shape or forming
projected portions on the metal plate 2101. A surface side face of
the aluminum-plate steel plate is subjected to fluorine coating
having a high anticontamination effect and a rear side face thereof
is subjected to black heat resistant coating having a high heat
absorbing effect.
[0222] The high frequency heat generating member 2103 is formed by
bringing a high frequency heat generating film 2103a comprising a
nitride and a boride generating heat by absorbing the high
frequency wave into close contact with a base member 2103b. A
material comprising a ceramic material or a heat resistant resin
material and having a high heat storing effect is preferably used
for the base member 2103.
[0223] The fixing members 2105 comprise insulating members provided
on the both sides along a direction of inserting the partition
plate 297 to the heating chamber 211 and by forming a gap between
the fixing member 2105 and the heating chamber 211, generation of
spark is prevented in high frequency heating.
[0224] Further, by constituting the metal plate 2101 by the wavy
shape, a distance between the high frequency absorbing film 2103a
and the metal plate 2101 is prolonged, thereby, an electric field
intensity on the high frequency absorbing film 2103a is increased
to thereby achieve also an effect of increasing a heat generating
amount on the high frequency absorbing film 2103a. Further, as the
high frequency heat generating member 2103, other than the
constitution of providing the high frequency heat generating film
2103a on the rear face, the high frequency heat generating member
per se may be formed by a ceramic generating heat by the high
frequency wave.
[0225] Although as the metal plate 2101, the aluminum-plated steel
plate made of metal is used, a base member of a ceramic material
provided with a layer of reflecting the high frequency wave by
metal plating, metal vapor deposition or the like can also be
utilized so far as a surface thereof reflects the high frequency
wave, further, stainless steel, aluminum and an aluminum alloy,
various steel plates of zinc-plated steel plate, aluminum zinc
alloy-plated steel plate, copper-plated steel plate and the like
and a clad material or the like can also be used. Further, although
a nitride or a boride is used as the high frequency absorbing film
281, a metal oxide of tin oxide, indium oxide or the like as well
as composite oxide or the like can also be used.
[0226] According to the high frequency heating apparatus 2200
having the above-described constitution, the heating chamber 211 is
divided into two spaces of an upper side space and a lower side
space and a desired heating processing can be carried out at the
respective spaces.
[0227] That is, according to the high frequency heating apparatus
2200, an upper side space 211a of the heating chamber 211 is
supplied with the high frequency wave of 5.8 GHz from the second
high frequency generating portion 215, further, a lower side space
211b of the heating chamber 211 is supplied with the high frequency
wave of 2.45 GHz from the first high frequency generating portion
213. The heated object M mounted on the partition plate 297 of the
upper side space 211a is heated by the high frequency wave of 5.8
GHz supplied from the upper side and also heated by heat generated
by the high frequency heat generating member 2103 by the high
frequency wave of 2.45 GHz supplied from the lower side. In this
case, so-to-speak grill cooking is carried out at the upper side
space 211a. On the other hand, at the lower side space 211b, by
mounting the heated object M on the bottom face of the heating
chamber 211, frequency heating of 2.45 GHz is carried out.
[0228] Further, there may be constructed a constitution in which
the high frequency heat generating member 2103 is not provided to
the partition plate 297. In that case, in the upper side space, the
heated object M can be heated to process mainly by the high
frequency heating from the upper side by restricting heating by the
high frequency from the lower side.
[0229] Further, the high frequency wave supplied from the upper
side may be constituted by the frequency of 5.8 GHz and the high
frequency wave supplied from the lower side may be constituted by
the frequency of 2.45 GHz.
[0230] According to the above-described constitution, other than
supplying the high frequency waves of the respective frequencies of
the common heating chamber 11, by respectively forming the
individual heating spaces 211a, 211b, heating by the high frequency
waves of the respective frequencies can be carried out individually
at the respective spaces 211a, 211b. Thereby, heating energy more
than necessary is not supplied by preparing a space more than
necessary relative to the size of the heated object M and by
setting the space to an arbitrary size, wasteless high frequency
heating can be carried out.
[0231] Further, a fixed type partition structure may be constituted
in place of the attachable and detachable partition plate 297 to
thereby construct a constitution of forming the individual heating
spaces by the high frequency waves of the respective frequencies.
In this case, operation of attaching and detaching the partition
plate 297 is not needed and heating operation can be
simplified.
[0232] Here, an explanation will be given of a constitution example
of simplifying the constitution of the high frequency driving
portion 217 of the high frequency heating apparatus 2100.
[0233] Although as shown by FIG. 17, the high frequency driving
portion 217 is respectively provided with the inverter circuits for
individually driving the respective magnetrons 225, 231, as shown
by other constitution example of the high frequency driving portion
shown in FIG. 26, there may be constructed a constitution of
driving the high frequency driving portion by a single inverter
circuit.
[0234] That is, there is constructed a constitution having the
drive control portion 2111 connected to an inverter circuit 2107
and controlling to switch a change over switch 2109 for switching
the magnetrons to be driven and enabling to output the high
frequency wave of 2.8 GHz and the high frequency wave of 2.45 GHz
by switching to control the change over switch 2109 at a pertinent
timing based on the signal from the control portion 219 (refer to
FIG. 16).
[0235] According to a high frequency driving portion 218 having the
above-described constitution, two different kinds of the magnetrons
225, 231 can be driven by the single inverter circuit and
therefore, the circuit constitution of the high frequency driving
portion 218 can considerably be simplified and a necessary
installing space is reduced, which can contribute to small-sized
and light-weighted formation of the apparatus.
[0236] An explanation will be given of controlling to drive the
first high frequency generating portion 213 and the second high
frequency generating portion 215 as follows.
[0237] The control portion 219 (refer to FIG. 16) outputs a signal
of distributing a power from the power source to the magnetron 225
for 2.45 GHz constituting the first high frequency generating
portion 213 and the magnetron 231 for 5.8 GHz constituting the
second high frequency generating portion 215 to the drive control
portion 273 (refer to FIG. 17) and the drive control portion 273
distributes to feed electricity to the first inverter circuit 237
and the second inverter circuit 267 by receiving the distribution
signal.
[0238] An explanation will be given of electricity feeding patterns
to the first high frequency generating portion 213, the second high
frequency generating portion 215 in this case in reference to FIG.
27 through FIG. 30.
[0239] FIG. 27 is a pattern of alternately outputting the high
frequency waves of 5.8 GHz and 2.45 GHz. According to the
electricity feeding pattern, the high frequency waves are outputted
alternately, both of the high frequency waves are not outputted
simultaneously and therefore, outputs of the respective high
frequency waves can be applied to output up to a rated power of the
high frequency heating apparatus. Therefore, the heated object can
efficiently be heated by making the outputs of the respective high
frequency generating portions by a maximum output.
[0240] FIG. 13 is a pattern of simultaneously outputting the high
frequency waves of 5.8 GHz and 2.45 GHz. The outputs in this case
are controlled such that a total power of the both high frequency
waves does not exceed the rated power of the high frequency heating
apparatus. In the drawing, there is shown a state of setting the
outputs of the both high frequency waves respectively to P/2 when
the rated power is designated by notation P. A rate of power
distribution can be set to an arbitrary rate, otherwise, further,
for example, the rate of the power distribution can be changed
after elapse of a predetermined time period.
[0241] FIG. 29 shows a pattern of precedingly outputting the high
frequency of 2.45 GHz and succeedingly outputting the high
frequency wave of 5.8 GHz. According to the pattern, at an initial
stage of heating at which a temperature of the heated object is
low, the temperature of the heated object is elevated in one motion
by supplying the high frequency wave of 2.45 GHz having a
comparatively high heating effect, further, the high frequency of
5.8 GHz is supplied after elapse of a predetermined time period or
after reaching a predetermined temperature, thereby, uniform
formation of the heating temperature is achieved and the uniform
heating state having a small temperature distribution can be
constituted. Further, there may be constituted a pattern of
precedingly outputting the high frequency wave of 5.8 GHz and
succeedingly outputting the high frequency wave of 2.45 GHz
contrary thereto. In this case, the pattern is preferable for
cooking of strongly heating the heated object at a later half of
heating. Further, in the case of simultaneously outputting the
respective high frequency waves at the later half of heating, there
may be constituted a pattern of alternately outputting the
respective high frequency waves as shown by FIG. 27. In that case,
the respective outputs can be applied up to the maximum
outputs.
[0242] FIG. 30 shows a pattern of outputting commonly the high
frequency wave of 5.8 GHz. The pattern is preferable particularly
for heating a thin-walled heated object and the heated object can
be finished in a state of having a small temperature distribution.
Further, there may be constituted a pattern of outputting only the
high frequency wave of 2.45 GHz. In this case, the high frequency
heating similar to that of the background art can be carried
out.
[0243] Although the invention has been explained in details in
reference to the specific embodiments, it is apparent for a skilled
person that the invention can variously be changed or modified
without deviating from the spirit and the range of the
invention.
[0244] The application is based on Japanese Patent Application No.
2003-121876 filed on Apr. 25, 2003, Japanese Patent Application No.
2003-130370 filed on May 8, 2003, Japanese Patent Application No.
2003-131804 filed on May 9, 2003, and a content thereof is
incorporated herein by reference.
INDUSTRIAL APPLICABILITY
[0245] According to the high frequency heating apparatus of the
invention, the distribution of the heating spots by the microwave
can be widened to a wider range of the heating chamber partitioned
by the cavity, the microwave is made to impinge on to a wider range
portion of the surface of the heated object.
[0246] As a result, even in the case of the microwave of 5.8 GHz
having a shallow baking depth, the substantial baking depth can be
intensified to double by heating the heated object from, for
example, both directions opposed to each other, and an irregularity
in heating can be prevented from being brought about over entire
regions of the surface layer and the inner depth portion of the
heated object without mounting the electromagnetic wave stirring
means in the heating chamber.
[0247] Therefore, excellent heating without a nonuiformity in
heating can be realized even for the thick-walled heated object,
and simplification of the structure and small-sized formation of
the apparatus in accordance therewith, or a reduction in
fabricating cost or running cost can be achieved by deleting the
electromagnetic stirring means.
[0248] Further, according to the high frequency heating apparatus
of the invention, the wide range wave guide in the shape of the
parallelepiped constituted by including a number of the feeding
ports is provided on the rear side of the heating chamber, the high
frequency generating portion is provided an immediate vicinity of
the wide range wave guide in the shape of the parallelepiped and
therefore, the structure of the wave guide is constituted by a
structure having the wide width and therefore, a number of feeding
ports can be provided and heating can be made to be proximate to
uniform heating.
[0249] Further, according to the invention, the wide range wave
guide in the shape of the parallelepiped is constituted by the size
widening substantially over an entire face of the floor portion and
a number of feeding ports are provided on the rear side of the
floor portion to direct to the side of the floor portion and
therefore, there is not brought about the difference in the
electric field intensity of the microwave between the center and
the corner of the heating chamber and heating can be made to be
proximate to uniform heating. Further, since the microwave is
irradiated from the floor portion and therefore, the irradiation is
proximate to the heated portion and also the heating efficiency is
improved.
[0250] Further, the constitution of a turn table, a rotational
antenna or the like for stirring radio wave may not be provided and
therefore, reliability against radio wave spark, radio wave leakage
or the like is also promoted.
[0251] Further, according to the invention, the wide range wave
guide in the shape of the parallelepiped is constituted by the size
widening substantially over the entire face of the ceiling and the
number of feeding ports are provided on the rear side of the
ceiling to direct to the side of the ceiling and therefore, uniform
radio wave falls from the single face of the ceiling as in a shower
and therefore, further uniform heating can be carried out.
[0252] Further, according to the invention, the frequency of the
high frequency wave supplied from the high frequency generating
portion is 5.8 GHz and therefore, in comparison with a case in
which a wave length of the microwave is 2.45 GHz constituting the
main current of the background art, the interval of the standing
waves is narrowed and heating can be made to be proximate to
further uniform heating.
[0253] Further, according to the invention, the size of the feeding
port is smaller at a vicinity of the high frequency generating
portion, the remoter from the high frequency generating portion,
the larger the size and therefore, there is not brought about a
difference in the electric field intensity of the microwave between
the portion proximate to the high frequency generating portion and
the portion remote from the high frequency generating portion and
heating can be made to be proximate further uniform heating.
[0254] Further, according to the high frequency heating apparatus
of the invention, there is provided the high frequency heating
apparatus for heating to process the heated object by supplying the
high frequency from the high frequency generating portion to the
heating chamber for containing the heated object, in which the high
frequency generating portion is provided with the first high
frequency generating portion for generating the high frequency wave
having the frequency of 2.45 GHz and the second high frequency
generating portion for generating the high frequency wave having
the frequency of 5.8 GHz, thereby, two kinds of the high frequency
waves of the high frequency wave having the frequency of 2.45 GHz
having a high heating effect and the high frequency wave having the
frequency of 5.8 GHz the heating distribution of which is uniform
can be supplied to the heating chamber, a nonuiformity in heating
is restrained from being brought about, and even the thick-walled
heated object can be heated to process swiftly and uniformly.
[0255] Further, according to the method of controlling the high
frequency heating apparatus of the invention, by supplying the high
frequency wave having the frequency of 2.45 GHz and the high
frequency wave having the frequency of 5.8 GHz to the heating
chamber simultaneously or alternately, the high frequency wave of
2.45 GHz having the high heating effect and the high frequency wave
of 5.8 GHz the uniform effect of which is high can selectively be
supplied and therefore, an efficient heating processing can be
carried out by supplying the pertinent high frequency wave in
accordance with the shape of the heated object and the object of
heating.
* * * * *